MIG/DEWANE LANDFILL

EPA ID# ILD980497788
Last Updated: September, 2014

Site Description

The 50-acre MIG/DeWane Landfill site is located about one-fifth mile east of the city of Belvidere and one-half mile north of U.S. Business Route 20 in Boone County, Illinois. Approximately 1,500 people live within one mile of the site.

The MIG/DeWane site consists of a 47-acre landfill and leachate impoundment system that was operated by various entities from 1969 until its abandonment in 1988 by M.I.G. Investments, the final operator. The landfill was a permitted municipal landfill and during its operating period it received household and municipal wastes as well as industrial wastes including paint sludge, volatile organic chemicals (VOCs), asbestos, and liquids containing heavy metals. In 1984, the U.S. Environmental Protection Agency (EPA)inspected the site and determined that the landfill waste and leachate were contaminating site soil, groundwater, and sediment and that the potential existed for surface water contamination and direct exposure of humans to contaminants.

After the landfill was closed in 1988, Illinois EPA inspected the site in 1989 and found that the site was not properly closed and capped, noting that there was exposed waste and a 5 to 10-acre depression in the middle of the landfill. The depression collected water that drained into the landfill and resulted in over one hundred leachate seeps with some leachate flowing off site towards the nearby Kishwaukee River. Illinois EPA's inspection also determined that the leachate surface impoundment was about to overflow and/or breach, which would potentially cause serious environmental impacts to the river. In 1989 and 1990, Illinois EPA and EPA, in two separate emergency actions, removed approximately 155,000 gallons of leachate from the site.

EPA placed the MIG/DeWane Landfill site on the Superfund National Priorities List in 1990.

Site Responsibility

The MIG/DeWane Landfill site is being addressed through potentially responsible party (PRP) actions under state and federal oversight.

Threats and Contaminants

Sampling results from the MIG/DeWane Landfill site indicate that soil, groundwater, sediment, leachate, and landfill gas are contaminated by VOCs and semi-VOCs, pesticides, polychlorinated biphenyl (PCBs), and inorganic (metal) compounds. A plume of groundwater contaminated with VOCs, semi-VOCs, and inorganic chemicals was found to be moving towards the Kishwaukee River. Exposure to contaminants by drinking contaminated water or coming into contact with contaminated soil or sediment could result in human health effects.

Cleanup Progress

In 1989 and 1990, Illinois EPA and EPA, in two separate emergency actions, removed approximately 155,000 gallons of leachate from the site.

EPA and Illinois EPA issued an Administrative Order on Consent in March 1991 to a number of potentially responsible parties (PRPs) to conduct interim cleanup actions at the site, which included the installation of an interim cap over the landfill, and to conduct a remedial investigation (RI) to determine the nature and extent of contamination. The order required the PRPs to stabilize the site prior to the start of the RI. The PRPs conducted several interim response actions from June 1991 to February 1993, including the installation of a security fence around the entire site, the removal of 50,000 gallons of leachate-contaminated ponded water from the top of the landfill and 240,000 additional gallons of leachate from the surface impoundment, the excavation of 3,500 cubic yards of off-site leachate-contaminated soil, the placement of the interim cap, the placement of topsoil and seeding, and the construction of temporary erosion controls both on and off site.

Early in 1999, landfill gas monitoring wells were installed along the western boundary of the soil borrow pit property west of and adjacent to the landfill. These monitoring wells detected landfill gas (methane) in the soil borrow pit and elevated levels of landfill gas were also detected in a few homes in the Wycliffe Estates subdivision west of the landfill. In April-May 1999, gas extraction wells, an interceptor trench, and a flare system were installed and activated to remove landfill gas that was moving off the site. The system significantly reduced landfill gas levels within a month's time. No landfill gas has since been detected in the subdivision.

After the RI was completed, EPA signed a Record of Decision (ROD) on March 31, 2000 to document its selected long term remedial action for the site that included the construction of a multilayer cap, the active and passive management of landfill gas, the installation of a localized leachate collection system, the removal of leachate and sediments from the leachate surface impoundment, and monitored natural attenuation of groundwater.

In December 2000, an addendum to the baseline risk assessment for methane and VOCs migrating from the site was completed. Using the collected groundwater and soil gas data, the Risk Assessment Addendum determined that the health risks were significantly lower than those presented in the March 1997 Baseline Risk Assessment and were less than EPA risk thresholds. As long as methane and VOCs in both groundwater and soil gas concentrations remain less than or equal to the levels measured in late 1999 to mid-2000, the indoor air pathway did not present an exposure pathway of concern. Overall, the methane gas levels continued to decline from 2000 through 2003. Most gas levels have reached non-detectable concentrations.

The PRPs signed a consent decree to conduct the cleanup actions in January 2006. The PRPs completed part of the Remedial Design work plan, but are waiting for comments from Illinois EPA before continuing the Remedial Design work.

Illinois EPA evaluated new information, including existing landfill cover thickness measurements, leachate levels, and groundwater data, that had been collected since the ROD was issued and then supported making a modification to the ROD remedy, which included making improvements to the existing interim landfill cover rather than installing the new cover system as described in the ROD. The improvements included placing additional compacted clay cover in areas on the side slopes consistent with the ROD remedy. The improved and graded areas would receive a minimum of six (6) inches of topsoil and be seeded to establish and sustain vegetative growth. No other modifications would be made to the ROD remedy. The changes were documented in an Explanation of Significant Differences (ESD) that Illinois EPA and EPA signed in August 2013.